1. Field of the Invention
This invention relates to a gas cigarette lighter, multi-purpose lighter or other such fire-lighting device that vaporizes fuel gas stored in a fuel tank and burns the vaporized gas as it is jetted from a jetting nozzle, particularly to the fuel supply device thereof.
2. Description of the Related Art
In a gas cigarette lighter, multi-purpose lighter or other such fire-lighting device, particularly in an internal combustion (premixed combustion system) fire-lighting device that effects ignition and burning after premixing air with the fuel gas jetted from the jetting nozzle, the opening of the jetting nozzle (nozzle plate) is made very small (diameter: 50-100 .mu.m) in order to jet gas at a high flow rate. Since this small-diameter portion is easily clogged by foreign matter, lighting (ignition) failure tends to occur because of insufficient gas jetting.
For overcoming this drawback, Japanese Utility Model Publication No.5(1993)-18609 teaches a technique of installing a filter made of woven or non-woven metallic fiber fabric upstream of the jetting nozzle or at the primary air intake so as to catch dust or other foreign matter before it can adhere to and clog the jetting nozzle.
The installation of such a filter made of woven or non-woven metallic fiber fabric does not, however, completely prevent the problem of lighting failure owing to clogging of the jetting nozzle.
To determine the specific reason for this, a fire-lighting device that experienced such nozzle clogging was disassembled and the foreign matter adhering to the jetting nozzle (nozzle plate) was analyzed. The analysis revealed the presence of dioctyl phthalate (DOP). DOP is a highly viscous substance commonly blended with rubber materials as a plasticizer and is generally contained in the O-rings, valve rubber and other rubber seal members used in a fire-lighting device.
When such rubber seal members come in contact with the fuel gas, DOP contained therein is eluted into the gas. Tests showed that when the fuel gas is jetted from the jetting nozzle to be burned, the gas pressure drives the eluted matter up to the jetting nozzle, where it adheres to and clogs the nozzle portion. Since the eluted DOP is in the form of a viscous liquid, the gas pressure can force some of it even through a metallic fiber filter membrane of the foregoing type installed in the fuel gas passage. It can therefore reach the small-diameter portion, where it adheres strongly owing to its high viscosity. The adhering DOP is not blown entirely away by the jetted gas but accumulates as an oily mass to obstruct jetting of the gas. It also catches ambient dust and other foreign particles that further obstruct gas jetting. As such, it is a cause of lighting failure.
Eluted plasticizer is not the only reason for clogging of the small-diameter portion of the jetting nozzle. Others causes include metal powder particles produced at the time of component machining and dust etc. that gets into the fire-lighting device during assembly.
In view of the foregoing problems, this invention aims to provide a fire-lighting device that effectively prevents clogging of the jetting nozzle in the gas passage by foreign matter.